IF YOU WERE RICH AND COULD AFFORD ANY WWII PLANE ...

Soren · Oct 5, 2006

davparlr said:
You mean the chart that Jank posted.The only chart I posted was a P-51B flight test chart. Which, by the way, is only one of many available, all with a tail numbers.

Whoops ! Sorry about that mate, I mistook that post as yours

The deviations of the chart you're talking about and the flight test data are disturbing and don't conform to typical engineering charts to performance.

Err, hows that ?

The charts you posted are Fw corporate charts that don't seem to specifically indicate that they contain flight test data, no tail number identified, no pilot identified, no discrete points noted. Do you have documentation that indicates these are really flight test results or or they engineering data. I must admit that the charts were fuzzy and I have to use a translator program.

I was actually talking about the P-51H charts.

All FW's charts are based on test-flights, and therefore they are never more than 4% off, that was the criteria at FW.

Okay, I used your data for the Fw-190D-9, your supplied chart for the P-51H, and my charts for the P-51B (1944) to generate the following chart:

Fw-190D-9 P-51H P-51B (1944)
Test Weight 9413 lbs (4270kg) 9544 (4329) 9680 (4472)
Empty Weight 7694 (3490) 6585 (2987) 6985 (3168)
Delta Weight 1719 (780) 2959 (1342) 2695 (1222)
Speed Max SL 380mph (612km/h) 400 (644) 371 (597)
Speed Max 436mph (702km/h) 453 (729) 442 (711)
Climb rate SL 4440 ft/min 4680 4350
Climb rate 16kft 3660 ft/min 3680 (18.7) 3580 (18.2)
climb to 10km 12.5 minutes 10 12.8
climb to 6km 5.4 4 6.4
Ceiling* 39k 41k 42k

Ceiling is not from flight test, but rather researched data.

I hope the chart works out. I have difficulties with charts. Please accept my appologies if it does not

Note that he tested weight over empty weight for the P-51H was over 2000 lbs more than the Fw-190D and the P-51B was carrying more than 1200 more. Imagine how the Fw-190Ds performance data would be impacted if it carried the same load weight.

This data shows what I said orginally.

The P-51H is faster at sea level and altitude, better climbing (and also has better power to weight ratio) and better ceiling. All of this while carrying 2000lb of bombs or fuel? I'll concede the turn. In fact it looks to me that the P-51B (1944 version) is quite comparable to the Fw-190D-9, especially at equivalent weight (although it doesn't have the firepower-perhaps balancing the weight difference with with a couple more 50 cals would work).

Using the data you supplied, I just don't see your justification to the superority of the Fw-190D-9 over the P-51H nor even more than slightly superior to the P-51B (1944 version).

So you still haven't convinced me with data. More attacks on the data?

davparlr, firstly how many P-51H's are there flying around today ?? And secondly lets take a look at what I said: "Nope, it wouldn't, and esp. not if my Dora's got GM-1, a D-12 prop and wheel doors, cause then I'd smoke any P-51 in a heartbeat. "

If you want it to be fair why not compare the P-51H to the Dora-12 (EB) ?

The Dora-12 (EB) will do approx. 25 m/s at SL, reach 10 km in approx. 9 min and hit 770+ km/h at 9.6 km.

davparlr · Oct 5, 2006

Soren said:
Whoops ! Sorry about that mate, I mistook that post as yours

No sweat.

Err, hows that ?

Engineering data should be similar as you reported on FW requirements. Normally you can expect errors but these are mitigated by comparing to flight test points (4% is reasonable, 7 or more is inexcusable). The seller would quickly lose favor with the buyer for that big an error and charges made. Of course during a war many things are overlooked.

I was actually talking about the P-51H charts.

All FW's charts are based on test-flights, and therefore they are never more than 4% off, that was the criteria at FW.

The data was reasonable

davparlr, firstly how many P-51H's are there flying around today ?? And secondly lets take a look at what I said: "Nope, it wouldn't, and esp. not if my Dora's got GM-1, a D-12 prop and wheel doors, cause then I'd smoke any P-51 in a heartbeat. "

Well, the H is not the definitive P-51 and there weren't nearly as many made or parts available. Everybody wants the D. Note that you never see a B flying around which performs better than the D when it is using the more potent fuel.

If you want it to be fair why not compare the P-51H to the Dora-12 (EB) ?

The Dora-12 (EB) will do approx. 25 m/s at SL, reach 10 km in approx. 9 min and hit 770+ km/h at 9.6 km.

Don't have too much data on these planes but the performance you have for them were impressive.

davparlr · Oct 6, 2006

Soren said:
Adler and Erich,

davparlr,

Instead of looking at that calculated chart why don't you take a look at what the P-51H 'really' could;
453 mph at 21,000 ft and 4,700 ft/min at sea level, 30,000 ft reached in 9½ min:

As an engineer, what has been bothering me is why the P-51H engineering charts deviated so greatly from test data (482 mph (776 kmh) to 453 mph (729 kmh). These guys were pros and would be unlikely to make such a large error. I think the deviation (identified on another site) is that the engineering charts reflect a clean aircraft (no racks) and the flight test were done with fuel and bomb racks attached. Flight test data on P-51Bs shows that max speed with racks was 431 mph and without racks, 444 mph. Therefore you can expect a greater impact at higher speed (I believe drag increases by the square of the speed), so it is reasonable to believe that the impact to the P-51H would be in the 15 mph range. This would raise the P-51H's top speed to 468 mph in test. This would bring the error to 3%, add in the typical engineering/marketing optimisim, and the engineering value makes sense.

Henk · Oct 6, 2006

I forgot I would also love a Dornier Do 335. Great looking aircraft and would love to fly one.

Soren · Oct 6, 2006

davparlr,

I have to agree its quite a blunder, but apperantly the guys at North American screwed that calculation up pretty bad cause it was for a clean aircraft.

Here's how their calculations looked later on in 1945 after some realizations had been made;
471 mph, thats a 16 mph drop in speed since the previous calculation:

davparlr · Oct 6, 2006

Soren said:
davparlr,

I have to agree its quite a blunder, but apperantly the guys at North American screwed that calculation up pretty bad cause it was for a clean aircraft.

Here's how their calculations looked later on in 1945 after some realizations had been made;
471 mph, thats a 16 mph drop in speed since the previous calculation:

This is not really a blunder. They claimed that a clean P-51H would do 487 mph clean. Based on the actual flight test data presented with racks (453 mph), 471 mph is about what I would have expected the P-51H to test at clean (I calculated 468). This is a reasonable error: 487-471=16 mph, or about 3% error, well within engineering error and would have also been found acceptable by FW. Like I said, engineering and marketing optimism always show better than actual performance (After 29 years of aircraft engineering, I can attest that if you do not use high risk high performance numbers and low cost, you will lose the contract!)

487 mph as a top speed for the P-51H is wide spread even by my reference book which has been very dependable. This chart is the only place I have seen that number officially. I would have never used engineering data as bonafide data point (I believe I flagged that when I first saw that chart, but, because of all the other references, I thought that they would certainly be based on actual flight test data). My feelings are, that in clean combat form, around 467-475 mph is the max speed for the P-51H. With racks, 447-455 mph.

However, this issue may apply to the data you have presented. If they are within 4%, you can see the impact. It dosen't seem to be actual flight test data (maybe with flight test input, just like the P-51H charts).

Also, like the Ta-152H, and the Fw-190D-9,11, the P-51H had great performance for a propeller power aircraft. All of these planes were at the peak of their design but were being overshadowed by the future, e.g., Me-262, P-80, Meteor, etc.

pasoleati · Oct 6, 2006

My take would be either the Boeing SeaRanger or the B&V 238. I´d build a moving home in them!

Soren · Oct 9, 2006

This is a reasonable error: 487-471=16 mph, or about 3% error, well within engineering error and would have also been found acceptable by FW.

davparlr, its a rather big error when you consider its from calculation to calculation - FW didn't accept such error's.

Henk · Oct 9, 2006

He he he........ Soren you loved to point that out.

davparlr · Oct 9, 2006

Soren said:
davparlr, its a rather big error when you consider its from calculation to calculation - FW didn't accept such error's.

What!! The only way we can calculate error, or to judge error, is to compare the calculated data to tested data in an equal situation, right? Well, the calculated data was made with no racks. There was no test data I could find that was performed with no racks so one to one comparison was impossible and error could not be determined or judged gross. To make errror analysis on one set of data that included no racks against those with racks would be incorrect and irresponsible. In order to fill in the unknown data, I looked for similar test on similar aircraft. I found that there was test performed on the P-51B with both racks and no racks. With an assumption that the racks were of similar design and impact to the P-51H, I calculated the corrected flight test point with no racks. Yes, this is a calculation. Yes, I am making a error analysis of calculated data against data I have calculated. But, the calculated data I used is based on solid engineering practice and flight test data. This is the best we have to make a judgment. You seem to want to make error analysis of a no rack performance against a flight test with racks. Would you judge error of calculated data with water injection with a flight test with no injection. At least I am saying that, by my calculations, this is within normal values. You say it is gross with no equal comparison capablity, and that would be irresponsible engineering evaluation. I hope you and Henk understand what I have just said.

kiwimac · Oct 10, 2006

109F, 190A and 190 D-9, Me 262, Ju 87; Re 2005; Fiat G.55; Macchi 200 and 205; Fiat Cr 42;
Hawker Hurricane.

FLYBOYJ · Oct 11, 2006

Gentlemen, gentlemen, you all have it wrong - PBY all the way and for obvious reasons....

DerAdlerIstGelandet · Oct 11, 2006

Like I said FBJ, Im with you! Ill take right seat!

FLYBOYJ · Oct 11, 2006

davparlr · Oct 11, 2006

There's plenty of room for more, or would you perfer to have a plane load of the feminine type?

FLYBOYJ · Oct 11, 2006

Feminine, but we'll make a few exceptions for a few friends...

MacArther · Oct 11, 2006

Sign me up!! I can be one of the waist gunners, and double as a negotiator in case the natives are not friendly.

Bf109_g · Oct 11, 2006

B.Mk.III Avro Lancaster!

Henk · Oct 11, 2006

Would love to be one of those friends.

the lancaster kicks ass · Oct 12, 2006

B.Mk.

it's one or the other, you can't have both, that's just greedy

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